JP4746496B2 - Wireless communication device - Google Patents

Description

  The present invention relates to a cognitive radio communication apparatus.

  With the development of the information society, the number of communication means that can be used in familiar scenes has increased dramatically, and the increase in communication speed has also been remarkable. While wireless communication is easily used, frequency resources are extremely depleted, and although ultra-high-speed wireless communication is purely technically easy, enormous efforts are required to perform within limited frequency resources. Yes.

  Corresponding to such a situation, a method of limiting an extremely wide band such as UWB (Ultra Wideband) to low-power short-range communication and opening it to overlap with other uses is recognized. In addition, even though there are not enough frequency resources, it is only insufficient on a license basis, and the time and place ratio where the licensed wireless communication device or system uses the frequency is not so much. There is an indication that it is not big. In response to such indications, research on cognitive radio systems that detect and use unused areas of the license system in terms of time and place has been started.

Since cognitive radio uses the frequency of the already licensed system, recognition of the radio wave environment in the vicinity of the own radio communication device is an important technical issue. For example, there is a method in which carrier sense is performed immediately before transmission at the frequency to be transmitted, and the frequency is changed if an interference wave exists at that frequency (see, for example, Patent Document 1). In a cognitive radio communication system, it is necessary to check whether or not a licensed radio communication apparatus is transmitting before transmission using a similar method.
Japanese Patent Laid-Open No. 08-288888

  Cognitive radio is a system that finds and uses the time and location gaps of the licensed system, so carrier sense before transmission needs to be taken carefully and carefully and must be detected with high accuracy. . On the other hand, when transmitting the own wireless communication device, if the transmission band of the own wireless communication device is at a frequency close to the band sensed by the own wireless communication device, the transmitted radio wave is received by the own wireless communication device. The carrier sense receiver falls due to saturation of the carrier sense receiver. However, if transmission cannot be performed during the carrier sense period, transmission efficiency will decrease.

  However, since the cognitive radio communication device uses the frequency of the already-licensed system, carrier sense should be performed before transmission to make sure that there is no communication of the licensed radio communication device in that band. . Further, depending on the transmission / reception multiplexing method, it is necessary to have a carrier sense receiver and a data reception receiver separately, which may increase the hardware scale.

  The present invention has been made in consideration of the above-described circumstances, and provides a cognitive radio communication device that maintains sufficient carrier sense performance and has high transmission efficiency while minimizing the hardware scale. The purpose is to provide.

In order to solve the above-described problem, the wireless communication apparatus of the present invention is configured to set a reception channel, a carrier sense channel, and a transmission channel from a plurality of bands obtained by dividing a usable frequency band into a plurality of bands. Setting means; second setting means for setting a reception center frequency of a reception signal; and setting a transmission center frequency of a transmission signal to the center frequency of the transmission channel; and reception means for receiving a reception signal received via an antenna; A first filter that filters two adjacent bands from the received signal; a reception baseband unit that performs reception processing on the filtered reception signal for a channel corresponding to the reception channel; and the filtered reception The signal is carrier sensed for a channel corresponding to the carrier sense channel. A carrier sense unit that performs processing, a transmission baseband unit that converts transmission data into a transmission signal, a second filter that filters the transmission signal in band units, and transmission that transmits the transmission signal via an antenna And a judging means for judging whether or not an elapsed time from the setting operation of the first setting means is equivalent to one time slot, the receiving channel and the carrier sense channel in the same time slot Are simultaneously set, the first setting means uses, as a reception channel, a first band that is one of the first band pairs composed of two adjacent bands of the plurality of bands. , A second band, which is the other band of the first band pair, is set as a carrier sense channel, and the second setting means includes: If the determination unit determines that the elapsed time is one time slot, the first setting unit sets the first center frequency to the previous time slot. A band used as a carrier sense channel is set as a transmission channel, and the carrier sense unit performs carrier sense in a time slot immediately before a time slot in which a transmission operation is performed. When it is determined that a part of the frequency of the sense channel is used, transmission in the next time slot is not performed at the frequency determined to be used .

  According to the wireless communication apparatus of the present invention, it is possible to maintain sufficient carrier sense performance and increase transmission efficiency while keeping the hardware scale to a necessary minimum.

Hereinafter, a wireless communication apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.
First, an outline of the wireless communication apparatus of this embodiment will be described.
The wireless communication apparatus according to the present embodiment divides a plurality of bands into time slots, and alternately performs carrier sense and transmission. The transmission timing is shifted in adjacent bands. Specifically, carrier sense is always performed before transmission. In the wireless communication apparatus, transmission is performed in one band, and reception and carrier sense can be performed simultaneously in two adjacent bands by one receiver. Although the wireless communication apparatus of this embodiment always performs carrier sense for a sufficient period before transmission, both the transmitter and the receiver can be used almost always, so that the transmission efficiency is improved and the transmission is performed. Since there is only one receiver and one receiver, the hardware scale is minimized. Further, the transmission / reception bandwidth can be set to the minimum necessary bandwidth.

  In the following drawings, portions directly related to the operation of the wireless communication device of the present embodiment are shown, and portions that are essential as a wireless communication system and a wireless communication device are not directly related to the essence of the operation of the present embodiment. Are omitted in the drawing and description.

Next, the wireless unit of the wireless communication apparatus of this embodiment will be described with reference to FIG.
The wireless unit 101 of the wireless communication apparatus according to the present embodiment includes a transmission baseband unit 102, an LPF (low-pass filter) 103, a frequency conversion unit 104, a PA (power amplifier) 105, a transmission antenna 106, a reception unit 107, an LPF 108, A frequency conversion unit 109, an LNA (low noise amplifier) 110, a reception antenna 111, a control unit 112, a reception baseband unit 113, a carrier sense unit 114, a local signal generation unit 115, and a database 116 are provided.

  The transmission baseband unit 102 converts data input for transmission into a baseband radio signal having a desired spectrum.

  The LPF 103 removes out-of-band spurious from the signal output from the transmission baseband unit 102. The bandwidth of the LPF 103 is approximately one band (band frequency width B in FIG. 3A).

  The frequency converter 104 converts the signal that has passed through the LPF 103 into a radio frequency. Although details of the frequency conversion unit 104 are not shown, this includes not only a mixer but also a gain adjustment unit, a filter, and a configuration for performing two-stage frequency conversion with an intermediate frequency in between as appropriate. Since the detailed configuration of the wireless communication apparatus is not an important point of the present embodiment, further detailed description is omitted.

  The PA 105 amplifies the signal converted into the radio frequency. The signal amplified by the PA 105 is radiated by the transmission antenna 106.

The LNA 110 amplifies the signal received by the receiving antenna 111.
The frequency conversion unit 109 converts the signal amplified by the LNA 110 into a baseband signal. The frequency conversion unit 109 may include various blocks in the same manner as the frequency conversion unit 104, but details are omitted. The bandwidth of the received signal converted into the baseband signal is 2B, that is, 2B for one band pair.

The LPF 108 removes a signal outside the reception band from the signal output from the frequency conversion unit 109.
The receiving unit 107 performs carrier sense processing and reception processing on the input signal.

  The control unit 112 grasps the frequency to be transmitted and the usage status thereof, and controls the transmission frequency and transmission performance / cancellation according to the usage status.

  Regarding the subsequent operations, first, the configuration of the band used by the wireless communication apparatus of the present embodiment and the outline of the usage method will be described with reference to FIGS. 3A, 3B, 4, 7A, 7B, and 7C. I will explain it later.

In FIG. 3A, the horizontal axis is frequency. The frequency range that can be used by the wireless communication system to which the wireless communication terminal of the present application belongs is divided into a plurality of bands. In the example of FIG. 3A, it is divided into 18 bands B1 ₁ , B2 _{1 to} B2 ₉ of width B. The width B of one band is, for example, 500 MHz. These bands form band pairs BP1 to BP17 between adjacent bands. Each band is basically included in two pairs: a band pair with an adjacent band on the low frequency side and a band pair with an adjacent band on the high frequency side. An exception is the band at the end of the frequency range, which is included in only one band pair. In FIG. 3A, every other band belongs to a different band group B1 or band group B2. Bands in different band groups have slightly different time slot usage.

  FIG. 3B shows an example of how to use the time slot of each band. Each band is divided into time slots in the time direction. One time slot is, for example, 20 μs. All band time slot boundaries are synchronized. In the example of FIG. 3B, carrier sense time slots and transmittable time slots are alternately assigned to each band, and carrier sense is always performed in that band immediately before transmission. Bands belonging to different band groups have different timings of transmittable time slots. Accordingly, in any band pair, one of the two bands included therein is one of the time slots for carrier sense and the other is a time slot capable of transmitting and receiving.

  A plurality of time slots (16 in FIG. 3B) form one frame. This time slot allocation is used in synchronism with radio communication apparatuses of the same standard and in a radio communication apparatus within a range where radio waves can reach each other. All wireless communication devices within the reach of radio waves are synchronized. Therefore, in the range in which radio waves reach, the control unit 112 in FIG. 1 performs control so that all wireless communication apparatuses do not transmit in the carrier sense time slot.

FIG. 4 is an example of how to use bands and time slots when the wireless communication apparatus of this embodiment performs reception, carrier sense, and transmission.
Each wireless communication device has a band and time slot for transmitting data and a band and time slot for receiving data, respectively. When transmission is performed in a certain time slot of a certain band, carrier sense is always performed in the previous time slot. The wireless communication device does not have a carrier sense dedicated receiver, and copes with it by extending the bandwidth of the data receiver. That is, transmission is performed in band units (bandwidth B), but reception is performed in band pair units (bandwidth 2B). Since carrier sense is performed in the time slot before the time slot transmitted in the transmission band, when trying to use the time slot effectively, another band that forms a band pair with the band in the time slot in which carrier sense is performed. Receive in one band.

  Of course, if the time slot is to be fully utilized, the other wireless communication device that transmits to the wireless communication device can receive in which band and time slot the own wireless communication device can receive. It is necessary to notify in advance. That is, the wireless communication apparatus determines a time slot in advance based on the reservation. In this embodiment, a protocol for establishing communication with the counterpart wireless communication device is not specified, but for example, by setting which band and in which time slot to communicate in advance by using a dedicated control channel, ISM band, etc. deep.

In the example of FIG. 4, the wireless communication apparatus uses a band pair BP1 composed of bands B1 ₁ and B2 ₁ and a band pair BP4 composed of bands B2 ₂ and B1 ₃ . As can be seen from FIG. 3A, BP1 and BP4 are slightly separated in frequency. That is, in a time slot in which reception / carrier sense is performed in either band pair, even if the own wireless communication apparatus transmits, transmission is performed in a band pair that is distant therefrom. As the frequency of the band pair that performs transmission and the frequency of the band pair that performs reception and carrier sense are farther from each other, the transmission signal is less likely to enter the reception, and good carrier sense can be performed.

  In the present embodiment, when transmission is performed in one band pair, neither reception nor carrier sense is performed in the band pair, so that the receiver is vacant. If reception and carrier sense in other band pairs are performed using the idle time, the transceiver can be used efficiently, and the transmission rate is improved. Further, since transmission and reception can be performed without interruption, QoS can be guaranteed.

  However, in the example shown in FIG. 4, two band pairs are used at the same time, but of course, only one band pair may be used. If only one band pair needs to be used in transmission / reception time division in terms of transmission rate, only one band pair may be used. The case where only one band pair is used will be described later with reference to FIG.

Wireless communication device of FIG. 4 is a first time slot S1 of the frame, it received at the band B1 _1, carrier sensing at the same time on the band B2 ₁ of the same band pair. At the same time out of the band pair BP4, transmit at B1 _3. In the next time slot S2, the carrier sense in band B2 ₁ made in S1, to transmit if it can result transmission carrier sense has been found. Thus, at time slot S2, without performing the band pair received or carrier sense in BP1, the reception at B2 ₂ of BP4, carrier sensing in B1 _3.

  Such an operation is repeated from time slots S1 to S6 in FIG. Of course, this may be repeated until the end of the frame. The features of this embodiment are best exhibited when transmission, reception, and carrier sense are efficiently packed as in time slots S1 to S6. That is, the transmission efficiency is the best because the transmitter and the receiver are almost always used even though a certain carrier sense period is always taken before transmission. Furthermore, since one transmitter and one receiver are provided, the hardware scale can be minimized. Further, the bandwidths of the transmitter and the receiver need only be the minimum necessary bandwidths, and each bandwidth is fully utilized when it is used most efficiently.

However, as a matter of course, a usage method that does not use some of all the time slots may be used, such as the time slot S7 and the following in FIG. In the example of FIG. 4, S7 does not use, repeatedly and carrier sense transmission and twice with S8~S11 in B1 _1, is performed once a carrier sense transmission and in B2 ₂ in between them. In S8, is not subjected to reception at B2 _1, receives collectively band pairs as receiver 107. In other portions, there is a portion where carrier sense and reception are not necessarily performed in the same time slot, but the reception unit 107 receives in band pair units.

Next, the frequency band used by the wireless communication apparatus of this embodiment will be described with reference to FIGS. 7A, 7B, and 7C with specific examples.
FIG. 7A shows that various license systems use frequency. Since the wireless communication apparatus according to the present embodiment is a wireless communication apparatus of a cognitive wireless system, it detects and uses a frequency temporal and spatial gap. Therefore, even if a band is used, the band cannot be used exclusively. When the band plan (FIG. 3A) of this embodiment is superimposed on FIG. 7A, the result is as shown in FIG. 7B. In each band, for example, as shown in FIG. Of course, it is not necessary to use all of the intervals, and only a part thereof may be used as shown in the lower part of FIG. 7C.

  In FIG. 7C, the frequency shown as the band used by the wireless communication apparatus of this embodiment is a band licensed to other systems in the first place. Therefore, the wireless communication device of the system licensed for that frequency has priority over that frequency. The wireless communication device of the cognitive wireless system according to the present embodiment needs to yield the frequency when the license wireless communication device starts transmission. The carrier sense time slot of this embodiment is so large that it occupies about half of the time, but this is to detect with high accuracy whether or not the licensed wireless communication apparatus has started transmission.

  The radio communication apparatus according to the present embodiment first performs carrier sense in a time slot before a time slot to be transmitted in a transmission band, and confirms whether there is no transmission at a frequency that the own radio communication apparatus intends to use. In the system of the present embodiment, the wireless communication device is synchronized with the time slot within the reach of the radio wave, and the allocation of the carrier sense time slot is also synchronized. Therefore, a certain frequency is used in the carrier sense time slot. If it is, it is understood that it is not at least that of the cognitive radio communication apparatus of the present embodiment. Of course, it is undeniable that the frequency used and found in the carrier sense time slot is that of a noise or other standard cognitive radio communication device, but it may be that of a licensed radio communication device. high.

  Therefore, the radio communication apparatus according to the present embodiment performs carrier sense in the carrier sense time slot immediately before transmission, and the frequency used in the carrier sense time slot is not used in the next transmission time slot. Of course, there is no need to stop transmission of the entire time slot, and it is only necessary to stop transmission of the used frequency or the surrounding band including the frequency. By doing so, the performance of not disturbing the transmission of the already-licensed system, which is an important element of the cognitive radio communication apparatus, is satisfied.

  In the present embodiment, carrier sensing is performed using a sufficiently long time as much as the time slot. By using this time, carrier sense can be performed with high accuracy, so that the licensed wireless communication device can be reliably detected and the transmission thereof can be prevented.

  In order to realize such a band configuration and usage, the receiving unit 107 having the configuration shown in FIG. 1 receives a band pair collectively. The receiving unit 107 divides the input signal into two and outputs it to the carrier sense unit 114 and the reception baseband unit 113. Usually, carrier sense and reception are performed simultaneously. However, depending on how the time slot is used, the receiving unit 107 performs carrier sensing without performing reception, or performs only reception without performing carrier sensing. Also in this case, the receiving unit 107 receives the band pairs together. Reception unit 107 includes a reception baseband unit 113 and a carrier sense unit 114. In addition, when bifurcating, the signal may be simply bifurcated, or may be branched in frequency bands, that is, in units of bands. Depending on the configuration of the reception baseband unit 113, the signal may be digitally processed. In this case, an analog-to-digital converter may be used depending on the design of the reception baseband unit 113. It is arranged in an appropriate part before or after inputting the signal.

  If there is a band for receiving data in the time slot, reception baseband section 113 demodulates and outputs the data signal transmitted in that band. If there is a possibility that interference waves other than transmission signals may overlap even though there is sufficient reception power at the time of demodulation, a licensed radio communication device having transmission priority at that frequency during reception Since the transmission may suddenly start, the control unit 112 is notified.

  The carrier sense unit 114 detects the usage status of the band for performing carrier sense in the time slot for performing carrier sense, which is instructed by the control unit 112. In particular, it detects whether there is no transmission by the licensed wireless communication device or other unknown wireless communication device regarding the frequency that the wireless communication device is going to transmit in the next time slot within the band. If transmission is detected, the control unit 112 is notified of the detection and its frequency. Upon receiving the notification, the control unit 112 controls the transmission baseband unit 102 to stop transmission at that frequency in the next time slot.

  As described above, the control unit 112 has a function of grasping the frequency to be transmitted and the usage state thereof, and controlling the transmission frequency and transmission execution / cancellation according to the usage state. Regarding carrier sense, the control unit 112 instructs the carrier sense unit 114 to collect information on the band usage status even in a time slot other than the time slot in which carrier sense is performed (for example, a vacant slot in FIG. 4 later). Then, carrier sense may be performed.

  The local signal generation unit 115 generates a local signal used for converting a transmission baseband signal into a radio frequency and a local signal used when converting a received signal into a baseband signal. When only one band pair is used and transmission / reception is performed in a time division manner, the frequency of the local signal input to the frequency conversion unit 104 and the frequency conversion unit 109 is constant. However, when the transmission / reception is switched for each time slot using two band pairs as shown in FIG. 4, the frequency conversion unit 104 and the frequency conversion unit 109 each time the transmission band pair and the reception band pair are switched. It is necessary to switch the local signal input to. Details of the local signal generation unit 115 will be described later with reference to FIG.

  The database 116 stores frequencies that are prohibited from being used in advance without performing carrier sense, such as frequencies of other systems that use radio waves but do not transmit radio waves. Also, in some cases, a frequency that is weaker to interference than other frequencies and requires special consideration of the use frequency is also stored. Note that the database 116 may not be provided in the wireless communication device but may be owned by another wireless terminal device or a database station connected via a network. The wireless communication apparatus according to the present embodiment accesses this database and refers to the content to serve as a basis for the control unit 112 to determine a use frequency or to control the carrier sense unit 114.

  The configuration of FIG. 1 is a very simple configuration showing basic functions. As a configuration of the wireless unit, an in-phase (I) component and a quadrature phase (Q) component may be individually handled in the baseband unit and combined and separated in the analog unit. Although details are not shown, in this case, since the system is divided into two systems of an I component and a Q component, the number of systems increases, and the bandwidth of the LPF becomes half that of FIG.

Next, an example of the local signal generation unit 115 in FIG. 1 will be described with reference to FIG.
For example, as shown in FIG. 2, the local signal generation unit 115 includes a frequency synthesizer 201, frequency division multipliers 202, 203, and 204, a crossbar switch (SW) 205, a frequency conversion unit 206, and a switch 207.

  The frequency synthesizer 201 receives a frequency reference, generates a single frequency signal synchronized with the frequency reference, branches the generated signal into three, and outputs it to each of the frequency multipliers 202, 203, and 204. Details of the frequency reference are not described here, but are, for example, a clock component extracted from the received signal, an independent crystal oscillator output, and the like.

  Frequency division multipliers 202 and 203 generate local signals used when radio signals are converted into baseband signals. In the case of the example of FIG. 4, the frequency signal for converting BP1 to baseband is generated by the frequency divider 202, and the frequency signal for converting BP4 to baseband is generated by the frequency multiplier 203. Further, the outputs of the frequency dividers 202 and 203 are also used for generating a local signal used when converting a baseband signal into a radio signal.

  That is, the two output signals of the frequency dividers 202 and 203 are input to the crossbar switch 205, and the two output signals are switched at the timing when the band pair is switched between transmission and reception. One output of the crossbar switch 205 is output to the frequency converter 206 and the switch 207. The other output of the crossbar switch 205 is output to the frequency converter 109 as it is, and is used when the received signal is converted into a baseband signal.

  The frequency divider 204 converts the output of the frequency synthesizer 201 into a frequency difference necessary for switching the bands in the band pair. For example, if the frequency width of the band is B, the frequency divider / multiplier 204 generates a frequency corresponding to the frequency width 2B of the band pair.

  The frequency conversion unit 206 mixes the output of the frequency divider / multiplier 204 and one of the two branched outputs of the crossbar switch 205 to generate a difference frequency or a sum frequency of these outputs. Whether the frequency converter 206 generates the difference frequency or the sum frequency depends on the design.

  The switch 207 inputs the output of the frequency converter 206 and the other one of the two branched outputs of the crossbar switch 205. The switch 207 outputs the output of the frequency converter 206 or the crossbar switch as an output to be passed to the frequency converter 104 every time the band pair used for transmission is switched to the high frequency side or the low frequency side. Switch to any of 205 outputs. The output of the switch 207 is input to the frequency converter 104 and used to convert the transmission baseband signal to a radio frequency.

Next, an example of the operation of the wireless communication apparatus when the wireless communication apparatus of the present embodiment performs communication using two band pairs will be described with reference to a flowchart of FIG. Here, the case where band pair BP1 and BP4 are used as an example is demonstrated. This operation corresponds to the time slots S1 to S6 in FIG.
Controller 112 sets the reception channel to B1 _1, sets the carrier sense channel B2 _1, sets the transmission channel B1 ₃ (step S501). The control unit 112 sets the conversion frequency of the frequency conversion unit 109 so as to convert the band pair BP1 (B1 ₁ + B2 ₁ ) into a baseband signal (step S502). Further, the control unit 112 sets the output center frequency of the frequency converting unit 104 to the center frequency of B1 ₃ (step S502). The control unit 112 resets a timer (not shown) (step S503).

Reception baseband section 113 performs reception processing in receiving channel B1 _1, the carrier sense unit 114 senses carriers with carrier sensing channel B2 _1, transmission baseband section 102 performs transmission processing in the transmission channel B1 ₃ (step S504 ).

  The control unit 112 determines whether or not there is an end interrupt command from an upper layer (not shown). If there is an end interrupt command, the communication is terminated, and there is no end interrupt command. In this case, the process proceeds to step S506 (step S505). The control unit 112 determines whether or not the timer reset in step S503 indicates that one time slot has elapsed. If one time slot has elapsed, the control unit 112 proceeds to step S507. If not, the process returns to step S504 (step S506). When one time slot has elapsed, the control unit 112 clears the settings of the reception channel, carrier sense channel, and transmission channel set in step S501 (step S507).

Control unit 112, new, for the next time slot, and sets the reception channel B2 _2, sets the carrier sense channel B1 _3, sets the transmission channel B2 ₁ (step S508). The control unit 112 sets the conversion frequency of the frequency conversion unit 109 so as to convert the band pair BP4 (B2 ₂ + B1 ₃ ) into a baseband signal (step S509). Further, the control unit 112 sets the output center frequency of the frequency converting unit 104 to the center frequency of B2 ₁ (step S509). The control unit 112 resets the timer (step S510).

Reception baseband section 113 performs reception processing in receiving channel B2 _2, the carrier sense unit 114 senses carriers in carrier sense channel B1 _3, the transmission baseband section 102 performs transmission processing in the transmission channel B2 ₁ (step S511 ).

  The control unit 112 determines whether or not there is an end interrupt command from the upper layer. If there is an end interrupt command, the control unit 112 terminates the communication. If there is no end interrupt command, the control unit 112 determines whether there is no end interrupt command. (Step S512). The control unit 112 determines whether or not the timer reset in step S510 indicates that one time slot has elapsed. If one time slot has elapsed, the control unit 112 proceeds to step S514. If not, the process returns to step S511 (step S513). If one time slot has elapsed, the control unit 112 clears the settings of the reception channel, carrier sense channel, and transmission channel set in step S508, and returns to step S501 (step S514).

  Next, an example of the operation of the wireless communication device when the wireless communication device of the present embodiment performs communication using one band pair will be described with reference to FIG. Here, a case where only the band pair BP1 is used will be described as an example. This operation corresponds to time slots S1 to S6 of only the band pair BP1 in FIG. Hereinafter, the same steps as those already described are denoted by the same reference numerals and description thereof is omitted.

The control unit 112 sets the reception channel to B1 ₁ and sets the carrier sense channel to B2 ₁ (step S601). The control unit 112 sets the conversion frequency of the frequency conversion unit 109 so as to convert the band pair BP1 (B1 ₁ + B2 ₁ ) into a baseband signal (step S602).
Reception baseband section 113 performs reception processing in receiving channel B1 _1, the carrier sense unit 114 is the carrier sense performs the carrier sense channel B2 ₁ (step S603).
The control unit 112 clears the setting of the reception channel and the carrier sense channel set in step S601 (step S604). Control unit 112 sets the transmission channel B2 ₁ (step S605). Control unit 112 sets the output center frequency of the frequency converting unit 104 to the center frequency of B2 ₁ (step S606).
Transmission baseband section 102 performs transmission processing in the transmission channel B2 ₁ (step S607).
The control unit 112 clears the transmission channel setting set in step S605 and returns to step S601 (step S608).

Next, a more detailed configuration / operation of this embodiment will be described.
(Time slot synchronization)
In FIG. 3B, the times of the time slot and the carrier sense time slot are synchronized by the wireless communication device within the reach of the radio wave. As a synchronization method, for example, all wireless communication devices to transmit transmit a known fixed pattern at the beginning of a time slot, and a wireless communication device to newly start transmission uses the fixed pattern in a radio wave environment detection procedure. Detect and detect the start time of the time slot and synchronize. The same applies to frame synchronization in the case where time slots are grouped in units of frames, and a fixed pattern indicating the beginning of the frame is transmitted at the beginning of the frame.

  If there is no other wireless communication device within the reach of the radio wave, that is, if a fixed pattern is not detected even after measurement for a certain time within the frequency range, if the wireless communication device wants to transmit, the time is at its own timing. Slots and frames are set. In addition, when other wireless communication devices are tuned, the positional range operating at that timing is expanded. In such a case, there is a group of wireless communication devices operating at different timings at different positions, and when a new wireless communication device starts operation at a position where radio waves reach both of them, which should be synchronized? The group of people who are confused and who do not synchronize either way will operate at incorrect timing. Which one to synchronize is, for example, synchronized with the person with whom the own wireless communication device wants to communicate, or if there is no other person with whom the wireless communication device is already transmitting Synchronize with.

  As a result of the synchronization, the problem that the radio wave with the shifted timing reaches the one that has not been synchronized may be solved by setting a certain procedure as follows. For example, it is assumed that a wireless communication device with different timing is detected while a certain wireless communication device is communicating. There are mainly three reasons why such a state occurs.

As described above, the first case is when the wireless communication apparatus sandwiched between the groups having different timings selects one of the timings, and thus the other group appears to have different timings.
Second, there is no other wireless communication device that is performing transmission within the range of radio waves of the wireless communication device that is about to start transmission. There is another wireless communication device in operation, and when the wireless communication device that tried to start transmission starts transmission at its own timing, the counterpart wireless communication device will return transmission in synchronization with the transmission timing addressed to itself Then, it is a case where timing deviates from other wireless communication devices in the vicinity of the counterpart wireless communication device.
Finally, when a certain wireless communication device starts transmission due to a difference in reception sensitivity or output power, it is determined that there is no other wireless communication device in operation around the own wireless communication device. In this case, the reception sensitivity is better than this (or the transmission power of the own wireless communication device is larger than the transmission power of the other wireless communication device), and the radio waves of the own wireless communication device reach the other wireless communication device. is there.

  The second case is the simplest. If communication parameters are set in advance using a dedicated control channel outside the communication band at the start of transmission, the synchronization detection information is exchanged in advance. This can be avoided. That is, communication can be started from the beginning in synchronization with the timing of the other wireless communication device detected by the counterpart wireless communication device. When there is no out-of-band dedicated channel and the first parameter is exchanged within the band, when the transmitting wireless communication device starts transmission at its own timing, the parameter is that transmission started at its own timing. If notified, the counterpart wireless communication device only needs to notify the transmitting wireless communication device that the timing is shifted and the correct timing when detecting that the transmission timing from the transmitting wireless communication device is shifted. . In this case, since it is desirable that the counterpart wireless communication device transmits at a timing synchronized with the surrounding wireless communication devices, the transmitting wireless communication device assumes various situations in which a response to its own transmission does not return at its own timing. It is good to be able to receive at the receiving timing.

  In the first case and the last case, the wireless communication device that has detected transmission at different timing changes the timing. It is difficult to notify the correct timing with radio waves to a wireless communication device that cannot detect the presence of other wireless communication devices due to reception sensitivity, and it is also possible to change the timing for a wireless communication device that has chosen a different timing with knowledge. Because it is difficult to do. Actually, if the transmission of the other wireless communication device is detected in the carrier sense time slot at the frequency to be transmitted by the own wireless communication device, the wireless communication device of the present embodiment stops the transmission in the next slot. Therefore, if it is detected that the detected signal is not from the licensed wireless communication apparatus but from another wireless communication apparatus with a shifted timing, the own wireless communication apparatus is connected to the communication partner and another wireless communication belonging to the same network. It is preferable to notify the device that the timing is changed and to change to the detected timing. As a result, the timing change of these wireless communication devices is the same as selecting a different timing for the first reason described above. As a result, the same operation is caused in all the wireless communication devices in the range where the surrounding radio waves reach, and the radio communication devices in the range where all the radio waves reach are synchronized. Whether the signal detected in the carrier sense time slot is that of another wireless communication device of the same standard with a shifted timing is determined based on whether or not a fixed pattern for detecting the time slot has been detected or the received content. do it.

  Note that the second reason, the first reason, and the third reason may occur at the same time, and the operations may compete to change the timing. In order to avoid such a situation, it is preferable to greatly change the time constant of the response to the second reason and the response to the first and third reasons. Desirably, the timing may be changed in a short time for the second reason, and in a longer time for the first and third.

(Bandwidth allocation)
Next, time slot allocation within a frame will be described.
First, when a plurality of wireless communication devices according to the present embodiment belong to the same network in an upper layer, for example, a data link layer, a parent wireless communication device for bandwidth allocation, for example, is selected between the wireless communication devices. Thus, band, time slot, and in-band frequency may be allocated. In this way, there is no transmission collision between wireless communication apparatuses belonging to at least the same network. The assigned time slot is continuously used as necessary, and when it becomes unnecessary, it is notified to the parent wireless communication device and released.

  When it is desired to move to another band for some reason, or when it is desired to use another frequency, the band to be moved and the frequency to be used may be reported to the parent wireless communication device and assigned. Since the parent wireless communication device does not always know the radio wave usage status including license terminal transmissions of all time slots of all bands, each radio communication device detects the radio wave usage status on its own, Report to the communication device. The same applies to the first assignment procedure, not only when moving.

  Therefore, the parent wireless communication device does not manage after grasping all the radio wave use conditions, but plays a role of adjusting the allocation so as not to collide. Considering that the parent wireless communication device has only such a simple function, it is not desirable that the network by the wireless communication device of the present embodiment extends over a wide area where radio waves do not reach each other, and if possible, radio waves reach each other. It is desirable to form a network with a range.

  Note that the band use method in the present embodiment can use only a part of the band frequencies as shown in the lower diagram of FIG. 7C. Therefore, it is possible for other wireless communication devices to use frequencies that are not used. Therefore, it is possible to assign the same band and the same time slot to a plurality of wireless terminal apparatuses on a frequency division basis. In the case of adopting a form that allows such in-band frequency division, the parent wireless communication apparatus may assign not only the band and time slot but also the in-band frequency when making the assignment.

(Reduction of collisions between other network wireless communication devices)
Further, in this embodiment, it is possible to insist on the continuous use of the time slot to another wireless communication device based on the implicit understanding without performing clear assignment, and the method will be described. That is, even between wireless communication devices that do not belong to the same network, it is possible to make it difficult for collisions to occur using frames.

  The transmissions assigned and used as described above are basically repeated in units of frames. Therefore, there is a high possibility that a band, a time slot, and an in-band frequency that have not been used in a certain frame are not used in the next frame. Therefore, when determining a transmission band, a time slot, and a frequency, a wireless communication apparatus that is about to start transmission first performs carrier sensing for one frame with the band, time slot, and frequency that it intends to transmit, It is preferable to start transmission from the next frame using a place that has not been used by other wireless communication apparatuses. In this case, another wireless communication apparatus may use it by chance. Such a collision probability is the same as the collision probability of Slotted Aloha, and is not so large when the range in which radio waves reach is narrow and the number of wireless communication devices is not very large. Therefore, by performing carrier sense for one frame in advance, transmission can be started with high probability without overlapping with other wireless communication devices.

(Non-framed form)
In the above example, the time slots are grouped into frames, but the frames are not essential and only need to have time slots. When there is no frame, it becomes difficult to pre-assign time slots in units that are repeated periodically, so that the band is used continuously (except for carrier sense time slots) or on a random access basis. It becomes the usage.

(Career sense time)
In FIG. 3B, every other carrier sense time slot is inserted in each band. If the license system of any band is less susceptible to interference than the other, for example, three carrier sensing time slots and a transmittable time slot 1 may be repeated in that band. Depending on how wide the band is, it is better to do so if the band width is about the bandwidth of one license system.

  If the band width is sufficiently larger than one average license system, and there is a license system that is less susceptible to interference than the other, the period during which no transmission is performed is increased only for the frequency of that license system. Take, that is, make the carrier sense longer. Even if a certain time slot can be transmitted, only a specific frequency is not transmitted. For example, if transmission is performed in one time slot, transmission is not performed for three time slots including the time slot for carrier sense. Time slots are used for transmission. Similarly, in the case of a license system that is particularly vulnerable to interference or a license system that performs carrier sense before transmission, the licensed wireless communication device cannot start transmission without a certain blank period, so sometimes a long interval is required. It is necessary to provide a period during which no data is transmitted. In that case, transmission may not be performed for the frequency in units of frames, for example.

  Each wireless communication device has information about such special frequencies in advance as data, and it is known in which time slot the frame can be transmitted and stopped. The wireless communication apparatus synchronizes.

  In the case of taking such an embodiment, the database 116 of FIG. 1 stores not only the spectrum mask but also the frequency band susceptible to interference in advance. The control unit 112 controls the carrier sense unit 114 so as to increase the carrier sense time for the frequency band stored in the database 116. As in the case of the spectrum mask, the database 116 is not provided in the wireless communication device, but may be owned by another wireless terminal device or a database station connected via a network. In this case, in the wireless communication apparatus according to the present embodiment, the control unit 112 controls the carrier sense unit 114 by accessing the database and referring to the content.

(Band pair movement)
Since the wireless communication system according to the present embodiment is a system that temporarily uses the frequency of another license system, when the other licensed wireless communication apparatus starts communication, the frequency must be surrendered. If the usage rate of a license system for one band pair suddenly increases and a band sufficient to answer the request of the wireless communication apparatus of this embodiment cannot be secured, it is necessary to move to another band pair. Alternatively, when a certain band pair cannot be used due to an increase in interference power by a wireless communication apparatus of another standard, for example, a UWB wireless communication apparatus, it is necessary to move to another band pair.

  When communication is performed using two band pairs as shown in FIG. 4, the frequencies of the two band pairs are separated to some extent as described above. Even when the UWB wireless communication apparatus starts transmission, it is unlikely that both band pairs are disabled at the same time. Therefore, in this embodiment, in such a case, the transmission / reception time division mode is temporarily shifted to a usable band pair. That is, communication is performed only with the band pair that can be used out of the two band pairs in FIG.

  For example, when only the band pair BP1 continues the communication, the content that is necessary to continue the communication among the contents communicated by the BP4 is moved to the band pair BP1. At this time, due to traffic temporarily moving from BP4, communication with low priority among the contents communicated by BP1 may be temporarily stopped or the rate may be reduced. In the transmission / reception time division mode in one band pair, since the receiver is vacant while performing the transmission operation, the carrier sense operation is performed on the band pairs other than the bands included in BP1 and BP4. In this case, the usage status of the time slot that can be transmitted is mainly measured. Of course, carrier sense of the paired carrier sense time slots may also be performed. However, in this case, since a new transmission possibility is searched, it is desired to grasp not only the transmission of the licensed wireless communication apparatus but also the transmission of another wireless communication apparatus. Since the transmission / reception time slot includes both transmissions, this is mainly inspected. When the frame configuration is used, the usage status of the band pair is measured at the time slot to be used.

  Next, when a band and a time slot that can be transmitted are found as a result of the measurement, the other party wishing to communicate is notified of the band. Similarly, the partner wireless communication device notifies the wireless communication device of the result detected by the partner wireless communication device. At this time, it is preferable to determine and notify the band pair to be measured in advance so that the selected band pair does not differ from the partner wireless communication apparatus.

  As can be seen from FIG. 4, when a new band pair is searched for using a receiver that is not available in the self-radio communication device while the self-radio communication device is transmitting, the self-radio communication device receives in that time slot. Since the machine is in a surplus state, reception is assigned. Therefore, the available wireless communication device uses the available band and time slot detected by the own wireless communication device for transmission. Similarly, the own wireless communication device performs transmission in the band and time slot detected as usable by the counterpart wireless communication device. In this case, as a matter of course, detailed band and time slot assignments, frequency utilization methods within each band, and the like are communicated with each other before starting communication in the band pair.

  When the mode returns to the two-band pair mode in this way, the transmissions packed in BP1 are dispersed, and the transmissions that have been canceled due to insufficient bandwidth or the rate has been reduced are restored. By using the two band pairs in combination in this way, communication can be continued even if one of the band pairs cannot be used. In the configuration of the present embodiment, even if two-band pairs are combined, the number of transmitters / receivers is not twice that required, and one system is sufficient for each. In the configuration of the present embodiment, since one system transmission / reception can be distributed over a plurality of bands, the continuity of communication is increased and QoS can be easily maintained.

(Time slot length)
The time slot length in the frame may be set to a value that is about the square root of the maximum number of wireless communication devices that may simultaneously transmit on the same network. For example, when the maximum number of wireless communication apparatuses is 256, the square root is 16. 256 wireless communication devices are arranged in a 16 × 16 matrix and divided into 16 groups for each row and 16 groups for each column. In one band pair, each group in each row transmits in one time slot, and in the other band pair, each group in each column transmits in one time slot. Is theoretically possible. (Of course, the throughput of each link is very small.) In this way, n: n communication becomes possible.

(Band pair formation when forbidden band is included)
Next, unlike the case where the bands are arranged without a gap in the frequency range as shown in FIG. 3A, a case where the forbidden band enters the middle of the frequency range will be described with reference to FIG.
In such a case, the combination of band pairs is temporarily cut at the forbidden band, and the bands at both ends of the forbidden band are included in only one band pair. In this embodiment, since two bands within a band pair are received simultaneously, a band pair cannot be formed even if bands that are separated in the middle are adjacent on the system.

  According to the embodiment shown above, the transmission efficiency is improved because both the transmitter and the receiver can be used almost always, although the carrier sense for a sufficient period is always performed before transmission, and Since there is one transmitter and one receiver, the hardware scale is minimized. In addition, the bandwidth can be the minimum necessary bandwidth corresponding to each transmission / reception bandwidth. Furthermore, even if the transmitter and the receiver are used at the same time, the frequency is always separated, so that the sensitivity of carrier sense does not decrease. Accordingly, the function of performing sufficient carrier sense as a cognitive radio communication device can be realized while the transmitter / receiver is kept to the minimum necessary configuration in terms of transmission rate.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The block diagram of the radio | wireless communication apparatus of this embodiment. The block diagram of the local signal generation part of FIG. The figure which shows the band structure which the radio | wireless communication apparatus of FIG. 1 utilizes. The figure which shows the time passage of the time slot in each band of FIG. 3A. The figure which shows an example of the usage pattern of a band and a time slot in case the radio | wireless communication apparatus of FIG. 1 performs reception, carrier sense, and transmission. The flowchart which shows an example of operation | movement in case the radio | wireless communication apparatus of FIG. 1 communicates using two band pairs. 2 is a flowchart illustrating an example of an operation when the wireless communication apparatus of FIG. 1 performs communication using one band pair. The figure which shows the frequency utilization condition of a license system in a certain frequency band. FIG. 7B is a diagram in which the band diagram of FIG. 3A is superimposed on FIG. 7A. It illustrates an example of a frequency band that the radio communication apparatus is utilized in Figure 1 in the band B1 ₁ in Figure 7B. The figure which shows a band structure when a forbidden band enters in the middle of a frequency range.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Radio | wireless part, 102 ... Transmission baseband part, 103 ... LPF, 104 ... Frequency conversion part, 105 ... PA, 106 ... Transmission antenna, 107 ... Reception part, 108 ... LPF, 109, 206 ... frequency conversion unit, 110 ... LNA, 111 ... reception antenna, 112 ... control unit, 113 ... reception baseband unit, 114 ... carrier Sense unit 115 ... Local signal generation unit 116 ... Database 201 ... Frequency synthesizer 202, 203, 204 ... Multiplier / multiplier 205 ... Crossbar switch 207 ... switch

Claims (7)

First setting means for setting a reception channel, a carrier sense channel, and a transmission channel from a plurality of bands obtained by dividing a usable frequency band into a plurality of bands;
Second setting means for setting a reception center frequency of the reception signal and setting a transmission center frequency of the transmission signal to the center frequency of the transmission channel;
Receiving means for receiving a received signal received via an antenna;
A first filter that filters two adjacent bands from the received signal;
A reception baseband unit that performs reception processing on the filtered reception signal for a channel corresponding to the reception channel;
A carrier sense unit that performs carrier sense processing on the filtered received signal for a channel corresponding to the carrier sense channel;
A transmission baseband unit for converting transmission data into a transmission signal;
A second filter for filtering the transmission signal in band units;
Transmitting means for transmitting the transmission signal via an antenna;
Determining means for determining whether or not an elapsed time after the first setting means performs the setting operation is one time slot;
When the reception channel and the carrier sense channel are simultaneously set in the same time slot, the first setting means is configured to use one band of a first band pair including two bands having adjacent frequencies among the plurality of bands. The first band is set as the reception channel, the second band, which is the other band of the first band pair, is set as the carrier sense channel, and the second setting means sets the reception center frequency. Set to the center frequency of the first band pair,
When the determination unit determines that the elapsed time is one time slot, the first setting unit sets a band used as a carrier sense channel in the immediately preceding time slot as a transmission channel ;
When the carrier sense unit determines that a wireless communication device belonging to another wireless communication system is using a part of the frequency of the carrier sense channel in the carrier sense in the time slot immediately before the time slot performing the transmission operation. The radio communication apparatus does not perform transmission in the next time slot at the frequency determined to be used . Regardless of whether or not they communicate with each other, multiple wireless communication devices within the range where they can receive each other's transmission radio waves synchronize time slots, and synchronize the band and time slot assignment used for the carrier sense channel The wireless communication apparatus according to claim 1, further comprising synchronization means for causing the wireless communication apparatus to perform the synchronization. When the first setting means sets the carrier sense channel or the reception channel and the transmission channel in the same time slot at the same time, the first setting means includes one of the second band pairs different from the first band pair. the wireless communication apparatus according to claim 1 or claim 2, characterized in that to set the band to the transmission channel. When it is found that one of the first band pair and the second band pair is disabled, the first setting means and the second setting means temporarily use only the other band pair. And a search means for searching for other usable band pairs in a time slot for transmission during a period in which only the other band pair is used. Item 4. The wireless communication device according to Item 3 . The synchronization unit synchronizes in units of frames including a plurality of time slots when a plurality of wireless terminal devices in a locational range where each other's transmission radio waves can be received belong to the same wireless communication system. The wireless communication apparatus according to any one of claims 2 to 4 . When the carrier sense unit newly starts transmission in one of the plurality of bands, the carrier sense unit performs carrier sense for one frame in the band and time slot, and a frequency and time slot that are not used by other terminals. 6. The radio communication apparatus according to claim 5 , wherein a transmission frequency and a transmission time slot in the next frame are selected based on the result of detection. The wireless communication according to claim 6 , further comprising scheduling means for predetermining a time slot for communication among a plurality of wireless communication devices belonging to a network for communication with each other based on a reservation. apparatus.

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